There is a need in the optoelectronics industry to provide for the latching and removal of optical transceiver modules inserted into cage on a customer board. One such module is known as a Parallel Fiber Optics Module (PFOM) and is designed to be z-pluggable into the cage of the customer board. These modules provide a transceiver function interfacing to optical signals with optical fibers. The new family of QSFP modules referred to above is described in the QSFP multi-source agreement (MSA), the contents of which are herein incorporated by reference, and available from the QSFP Chair and Editor, McData Corporation, 4 McData Parkway, Broomfield, Colo. 80021.
A typical cage 10 and a printed circuit board (PCB) 12 are shown in FIGS. 1A and 1B, along with inserted module 14. The module 14 has an edge connector which plugs into a complementary edge connector on the printed circuit board. As will be seen in FIG. 1B, the QSFP module is inserted into the cage 10 mounted on the PCT 12. Both examples are for QSFP modules.
The QSFP is a z-pluggable module. This offers attractive features for the customer:
                a) By fitting into a pre-assembled cage on the customer board and being readily installed and removed, it allows ports to be populated on demand and also offers ease of in-the-field replacement.        b) It offers significant improvements in board and edge area density and power consumption as compared to serial SFP based solutions where four discrete SFPs would be required.        c) It provides a customer management interface in the same way as SFP modules.        
The QSFP is intended to be fitted with a bail-latching mechanism, though this is not defined in detail within the MSA, and hence this is being left to the market to decide on a suitable solution.
Latch mechanisms are used today in a variety of z-pluggable modules, e.g. SFP and XFP modules. The QSFP solution, however, presents unique problems that have not been encountered previously as no family of z-pluggable modules has previously been developed. Z-pluggable modules are modules that can be plugged into the front panel of a housing 16, as shown in FIG. 2.
The main problem relates to the optical fiber. The QSFP is a PFOM based module, and as such uses an industry standard MPO/MTP fiber connector as is used in all multiple fiber ribbon cables. The MPO/MTP is a spring-loaded connector that snaps into the receptacle of the QSFP. Insertion is relatively straightforward. Removal or de-insertion requires a sliding section on the connector to be drawn back which disengages the connector, thus allowing removal. This in itself is not a problem. However, problems arise when the end-user desires to use multiple QSFPs in a high density solution. Three example scenarios of close packed solutions are:                a) Ganged: QSFP modules are placed adjacent to one another        b) Stacked: when QSFP modules are placed on top of each other        c) Belly-to-Belly: this is when QSFP modules are placed on either side of a PCB. A typical Belly-to-Belly solution is shown in FIG. 2.        
In all the above high packing density configurations, the problem becomes how to remove the optical fiber from modules away from the outer corners. At maximum packing density it is not possible for the optical fiber to be readily removed from an inner module 14 inserted into the corresponding cage 10 Therefore under normal conditions the end-user is forced to trade-off density against ergonomic practicalities for the QSFP. The difficulty of removing the optical fiber has a knock-on effect in that it also means that the QSFP module cannot be removed using conventional bail latching mechanisms since this requires movement of the latch that is precluded by the presence of the optical fiber. The inability to remove the QSFP module when the fiber is attached is a significant problem.